Preheat oven to 350°F and line 2 baking sheets with parchment paper.
In a medium bowl, combine oats, flour, salt, baking soda, and spices. Set aside.
In the bowl of a standing or handheld mixer, beat the butter, brown sugar, and granulated sugar until light and fluffy, around 2 minutes.
Mix in the egg and vanilla, then slowly mix in the dry ingredients until just combined (don't over-mix! Over-mixing will lead to dense cookies). The dough will be sticky.
Fold in the chocolate and then make 3 tbsp sized balls of dough and place them on the baking sheet. Leave room in between each one for them to spread! Gently press down on top of each cookie to flatten them slightly.
Bake one sheet at a time for 8-11 minutes or until the outside edges are set. Do not over-bake! Leave the cookies on the baking sheet for 5 minutes then transfer to a cooling rack to cool completely.